1. Field of the Invention
This invention relates to a magnetic recording medium effective for a width direction recording system and a process of producing such a magnetic recording medium.
2. DESCRIPTION OF THE PRIOR ARTS
Recently, magnetic recording media as well as the recording and reproducing techniques have made remarkable progress and new techniques about, in particular, perpendicular magnetic recording system, super thin magnetic medium by plating, vacuum vapor deposition, etc., and integrated heat, etc., are progressing for practical use.
In addition to such technical tendency, a magnetic recording system tends to change the situation from an AC bias system and a helical scanning system to a PCM fixed head V. T. R. system.
Also, under such circumstances, a system of recording and reproducing in the width direction of a magnetic recording tape is now under investigation. That is, as shown in FIG. 1 and FIG. 2 of the accompanying drawings, in the foregoing system, head gaps are disposed in the vertical direction to the lengthwise direction, i.e., the travelling direction of a magnetic recording medium or tape and magnetized patterns are formed in the width direction of the recording medium. Such a magnetic recording system has the features that the positioning accuracy is improved for width direction tracks and perpendicular magnetizable components are liable to be easily magnetized as compared to a longitudinal direction recording system, and hence is being watched as a system having bright future.
However, a conventional magnetic recording medium most widely used at present is one prepared by coating a coating composition composed of ferromagnetic particles dispersed in a binder on a web support of a high molecular compound as typified by cassette tape and video tape. Furthermore, for improving the recording and reproducing characteristics in the longitudinal direction, various efforts have been made for improving the coercive force Hc, the residual magnetic flux density Br, and the squareness ratio Br/Bm in the longitudinal direction.
Also, since a magnetic orientation method has been employed for improving these magnetic characteristics, the ratio of the width direction residual magnetic flux density Br.sub.t to the longitudinal direction residual magnetic flux density Br.sub.l is less than 1. Therefore, such a magnetic recording medium does not show preferred magnetic characteristics for width direction recording and the SN ratio obtained by such a recording medium is only the values less than 20 dB as shown by black dots in FIG. 3.
Moreover, a coating type magnetic recording medium has the property that the magnetic particles arrange of oneself in the longitudinal direction by the shearing stress at coating even when a magnetic orientation treatment is not applied at coating and hence a magnetic recording medium of Br.sub.t &gt;Br.sub.l can not be principally obtained.